﻿/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

using Aliyun.Acs.Core.Retry.Condition;

namespace Aliyun.Acs.Core.Retry.BackoffStrategy
{
    public class BackoffStrategyHandler : IAlibabaBackoffStrategy
    {
        // Unit is milliseconds
        private const int SdkDefaultBaseDelay = 100;
        private const int SdkDefaultThrottledBaseDelay = 500;
        private const int SdkDefaultMaxBackoff = 20 * 1000;

        private readonly ExponentialBackoffStrategy exponentialBackoffStrategy;
        private readonly JitteredExponentialBackoffStrategy jitteredExponentialBackoffStrategy;

        public BackoffStrategyHandler()
        {
            exponentialBackoffStrategy = new ExponentialBackoffStrategy(SdkDefaultBaseDelay, SdkDefaultMaxBackoff);
            jitteredExponentialBackoffStrategy =
                new JitteredExponentialBackoffStrategy(SdkDefaultThrottledBaseDelay, SdkDefaultMaxBackoff);
        }

        public int GetDelayTimeBeforeNextRetry(RetryPolicyContext retryPolicyContext)
        {
            var retryable = retryPolicyContext.Retryable;

            if ((retryable & RetryCondition.ShouldRetryWithThrottlingBackoff) == RetryCondition.ShouldRetryWithThrottlingBackoff)
            {
                return exponentialBackoffStrategy.GetDelayTimeBeforeNextRetry(retryPolicyContext);
            }

            return jitteredExponentialBackoffStrategy.GetDelayTimeBeforeNextRetry(retryPolicyContext);
        }
    }
}
